What Is a Forest Carbon Stock Calculator?
This calculator estimates how much carbon, expressed as tons of CO2 equivalent, is stored in a forest stand's live tree biomass. It follows the standard forestry approach: start from measured merchantable timber volume, scale it up to account for the whole tree (branches, foliage and roots), then convert dry biomass to carbon and finally to CO2 equivalent — the same general method behind IPCC-aligned forest carbon inventories.
This estimate covers live tree biomass only. It does not include soil carbon, deadwood, litter, or understory vegetation, which a full forest carbon inventory would also measure.
How to Read Your Results
Carbon Stock (CO2 Equivalent)
The headline number: total estimated carbon stored in the stand's trees, converted to tons of CO2 equivalent — the standard unit used in carbon accounting and offset markets.
Total Biomass
The estimated total dry weight of tree material in the stand, including above-ground parts and roots, before converting to carbon.
Carbon Stored
Total biomass converted to elemental carbon using the standard 47% carbon fraction of dry wood biomass.
Above-Ground Biomass
The biomass estimate before adding roots — derived directly from timber volume, wood density and the biomass expansion factor.
Real-World Example
A forest stand has 500 m³ of merchantable timber volume, a wood density of 0.5 tons/m³ (typical for many temperate hardwoods), a biomass expansion factor of 1.3, and a root-to-shoot ratio of 0.24.
| Step | Result |
|---|---|
| Above-ground biomass (500 × 0.5 × 1.3) | 325 tons |
| Total biomass (× 1.24 for roots) | ≈403 tons |
| Carbon (× 0.47) | ≈189.4 tons C |
| CO2 equivalent (× 3.67) | ≈695.3 tons CO2e |
This stand stores an estimated 695 tons of CO2 equivalent in its live tree biomass — roughly the annual emissions of dozens of passenger vehicles, illustrating why standing forests are considered significant carbon sinks.
Tips for Estimating Forest Carbon
- Wood density varies by species — softwoods often run lower (around 0.35–0.45 tons/m³) than many hardwoods (0.5–0.65 tons/m³).
- Biomass expansion factors are typically higher for younger, smaller-diameter stands and lower for mature stands with more merchantable volume relative to branches.
- Root-to-shoot ratio varies by forest type — drier or more stressed forests often allocate relatively more biomass to roots.
- This tool estimates live tree carbon only — full stand carbon also includes soil, deadwood and litter, often a substantial additional pool.
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Last updated: August 2026 · Reviewed by: Simple Calculator Tools Editorial Team